The alphanumeric telephone keypad matrix is known in the art. The universally recognized standard for the push button telephone keypad is a 4.times.3 matrix having four rows and three columns of buttons, or keys Each key (except the "1" *, # and "0" keys) is preassigned with a single digit or special symbol as a primary assignment, and with three alphabetic characters as a secondary functional assignment.
Automatic response function telephone systems, computerized systems, are designed to route incoming calls from pay or non-pay calling stations to a computer. An incoming call is received and processed by the computer which typically prompts the caller to select the desired service by pressing numeric keys on the telephone keypad. The identity of each numerical key is determined from an analog, dual tone multifrequency signal (DTMF) which is generated upon depressing the numerical key. The DTMF is a combination of two analog voice frequency tones, and it addresses stored digital code. Timing is typically not critical in the entry of DTMF signals for the identification of the numerals of standard, numerical keys. The computer converts the analog DTMF tones into digit signals for processing. The computer may also convert digit signals into analog voice signals for providing acknowledgement/prompt messages to the caller.
For example, by pressing the numeral 1 on the keypad in response to a computerized voice prompt, the caller may be connected to the technical support department, or by pressing the 0 on the keypad, the caller may be connected to an operator for further assistance. Computerized telephone systems may also eliminate voice communication and require the caller to communicate exclusively through the telephone keypad. In one such application wherein a caller desires that information be delivered by facsimile, the caller may press the number key corresponding to the number of the desired document and, upon entry of the start button or the receiving facsimile number, the document will be delivered.
Entry of the letters of the alphabet is desirable for many reasons and purposes, including automatic response function telephone systems. For example, the caller's name and address may be needed to complete a telephone transaction.
While the universally recognized 4.times.3 keypad of the prior art standardizes the physical arrangement of the numeric characters, the physical arrangement of alphabetic characters may vary. One typical push button telephone matrix of the prior art includes twenty four letters of the alphabet, excluding the "Q" and the "Z" arranged on eight of the twelve keys as follows:
______________________________________ KEY 1 No letters KEY 2 ABC KEY 3 DEF KEY 4 GHI KEY 5 JKL KEY 6 MNO KEY 7 PRS KEY 8 TUV KEY 9 WXY KEY 0 No letters KEY * No letters KEY # No letters ______________________________________
There are several methods of entering alphabetical characters using the conventional telephone keypad design outlined above. None of the methods provides for the DTMF signal entry of alphabetical characters.
The first method requires the caller to locate the desired letter on the telephone keypad, press the corresponding key either once, twice, three, or four times, depending upon the location of the desired letter on the key, and then to press the a symbol key, such as the pound sign key, which operates as a signal code to indicate the desire to enter a character as opposed to a digit. This method is shown in the Hashimoto et al. U.S. Pat. No. 4,658,417. For example, to enter the name "JONES" using the Hashimoto method, the following steps are required:
______________________________________ "J" KEY 5 Press twice # KEY Press once "O" KEY 6 Press four times # KEY Press once "N" KEY 6 Press three times # KEY Press once "E" KEY 3 Press three times # KEY Press once "S" KEY 7 Press four times # KEY Press once ______________________________________
Because a separate symbol key, such as the pound sign key, must be pressed before entry of the next desired letter, the caller's concentration on the word to be communicated is interrupted after entry of each letter within the word. Considerable concentration is required to correctly complete the desired entry.
A second method for entering letters of the alphabet requires the caller to locate and press the key bearing the desired letter and then to press the key bearing the numeral corresponding to the position of the desired letter on the key. For example, to enter the letter "H", the caller must first press the number four key which bears the letter "H", and must then press the number two key because the "H" is the "second" letter on the number four key. The following steps are required to enter the name "JONES" using the second method:
______________________________________ "J" KEY 5 Press once KEY 1 Press once (Pause) "O" KEY 6 Press once KEY 3 Press once (Pause) "N" KEY 6 Press once KEY 2 Press once (Pause) "E" KEY 3 Press once KEY 2 Press once (Pause) "S" KEY 7 Press once KEY 3 Press once ______________________________________
Although the second method standardizes the number of keystrokes for each letter, the user's concentration is interrupted be the requirement to press a digital key between letters. Considerable concentration is required to properly complete the required keystrokes.
As can be seen from the above summary of the prior art, an unsolved need exists for a simple method for inputting alphabetical characters into a telephone system using the existing telephone keypad.